Rust polars 0.26 is released

After almost 2 months of work a new polars release is issued spanning more than 250 commits from 30 contributors. A big thank you to everybody that helped in this effort!

Most notable this release is that streaming/out-of-core support is getting better, more stable and really fast (in some cases up to 4x faster than our default engine). Currently we support out of core filters, projections, joins and groupbys and we want to extend to sorting as well. If your query cannot be done out-of-core we fallback to the default engine, which is also very fast. :)